Roll Massif

Cycling involves a surprising amount of math, but fortunately, you don’t have to do it. Welcome to Roll Massif, where we handle the headaches of gear ratios, sprocket math, and tire pressure physics for you. Whether you are trying to justify the cost of a used bike, figuring out how many calories that climb burned, or tweaking your Time Trial fit down to the millimeter, we’ve got a calculator for that.

Skid Patch
Stack to Reach
Gear Ratio

Roll Massif Fixed Gear Optimizer

Check tire wear and gear speed instantly.

Chainring (Teeth)

Rear Cog (Teeth)

Tire Size

Ambidextrous Skidding (Both feet)

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Gear Inches —

Speed @ 90rpm —

mph / km/h

Stack-to-Reach Ratio is a fundamental and simple metric for cyclists to understand how a frame will “feel” without actually sitting on it.

Ratio Calculator

STACK (mm) REACH (mm)

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Here is the Fixed Gear Ratio Calculator

Popular Drivetrains

Common Wheel Sizes (Dia In)

Chainring

Rear Cog

Wheel Dia (In)

Cadence (RPM)

Crank Length (mm)

Ratio	–
Skid Patches –	–
Gear Inches –	–
Gain Ratio –	–
Speed (MPH / KMH)	– / –

Cadence Reference (MPH / KMH)

Type	RPM	Speed Results
Recovery	70	–
Efficient Cruise	90	–
Sprinting	120	–
Downhill/Emergency	140	–

Saved in Memory

Setup	Ratio	Skid	MPH / KMH